Translocation breakpoint possibly predisposes to nonrandom X-chromosome inactivation in mouse embryos bearing Searle's T(X;16)16H translocation

To clarify the sequence of events that ultimately achieves the nonrandom inactivation of the paternally inherited X chromosome in postpartum female mice heterozygous for T(X;16)16H, we set out to examine the expression of Xist alleles and the X-linked HMG-lacZ transgene in embryos recovered at the egg cylinder stage. Lack of expression of the Xist(b) allele on the 16X translocation chromosome in the embryonic region of 7.5 d postcoitum (dpc) X16/X(n)Xist(a);16(X)Xist(b)/16 embryos strongly suggested the occurrence of nonrandom inactivation in favor of the normal X chromosome. The simplest explanation would be biased choice, followed by postinactivation selection against genetically unbalanced cells. However, the frequency and distribution of beta-galactosidase-positive cells in X16/X(n)lacZ;16X/16 embryos at 6.5 and 7.5 dpc, together with earlier cytogenetic data, raised an intriguing possibility that the majority of 16X chromosomes were prevented from completing the inactivation process, when they had been chosen to be silenced. Phenotypes of female mice carrying a spontaneous recombination between Xn and 16X in the segment defined by the T16H breakpoint and the X-linked Ta locus suggested that the nonrandomness was brought about by disruption of an X-chromosomal sequence or structure at the translocation breakpoint.

X-chromosome inactivation in XX androgenetic mouse embryos surviving implantation

Using genetic and cytogenetic markers, we assessed early development and X-chromosome inactivation (X-inactivation) in XX mouse androgenones produced by pronuclear transfer. Contrary to the current view, XX androgenones are capable of surviving to embryonic day 7.5, achieving basically random X-inactivation in all tissues including those derived from the trophectoderm and primitive endoderm that are characterized by paternal X-activation in fertilized embryos. This finding supports the hypothesis that in fertilized female embryos, the maternal X chromosome remains active until the blastocyst stage because of a rigid imprint that prevents inactivation, whereas the paternal X chromosome is preferentially inactivated in extra-embryonic tissues owing to lack of such imprint. In spite of random X-inactivation in XX androgenones, FISH analyses revealed expression of stable Xist RNA from every X chromosome in XX and XY androgenonetic embryos from the four-cell to morula stage. Although the occurrence of inappropriate X-inactivation was further suggested by the finding that Xist continues ectopic expression in a proportion of cells from XX and XY androgenones at the blastocyst and the early egg cylinder stage, a replication banding study failed to provide positive evidence for inappropriate X-inactivation at E6. 5.

Extracardiac total cavopulmonary connection after superior cavopulmonary connection for left isomerism

We report the case of a 3-year-old boy who underwent definitive conversion to the Fontan circulation after total cavopulmonary shunt using a total extracardiac right heart bypass. This simple, safe and reproducible procedure is an alternative to Fontan or total cavopulmonary connection procedure.

Imprint switching for non-random X-chromosome inactivation during mouse oocyte growth

In mammals, X-chromosome inactivation occurs in all female cells, leaving only a single active X chromosome. This serves to equalise the dosage of X-linked genes in male and female cells. In the mouse, the paternally derived X chromosome (X(P)) is imprinted and preferentially inactivated in the extraembryonic tissues whereas in the embryonic tissues inactivation is random. To investigate how X(P) is chosen as an inactivated X chromosome in the extraembryonic cells, we have produced experimental embryos by serial nuclear transplantation from non-growing (ng) oocytes and fully grown (fg) oocytes, in which the X chromosomes are marked with (1) an X-linked lacZ reporter gene to assay X-chromosome activity, or (2) the Rb(X.9)6H translocation as a cytogenetic marker for studying replication timing. In the extraembryonic tissues of these ng/fg embryos, the maternal X chromosome (X(M)) derived from the ng oocyte was preferentially inactivated whereas that from the fg oocyte remained active. However, in the embryonic tissues, X inactivation was random. This suggests that (1) a maternal imprint is set on the X(M) during oocyte growth, (2) the maternal imprint serves to render the X(M) resistant to inactivation in the extraembryonic tissues and (3) the X(M) derived from an ng oocyte resembles a normal X(P).

Maternally inherited X chromosome is not inactivated in mouse blastocysts due to parental imprinting

Mouse embryos having an additional maternally inherited X chromosome (X(M)) invariably die before midgestation with the deficient extraembryonic ectoderm of the polar trophectoderm lineage, whereas postnatal mice having an additional paternally inherited X chromosome (X(P)) survive beyond parturition. A cytogenetic study led us to hypothesize that abnormal development of such embryos disomic for X(M) (DsX(M)) is attributable to two doses of active X(M) chromosome in extraembryonic tissues. To test the validity of this hypothesis, we examined the initial X chromosome inactivation pattern in embryos at the blastocyst stage by means of replication banding method as well as RNA FISH detecting Xist transcripts. X(P) was the only asynchronously replicating X chromosome, if any, in X(M)X(M)X(P) blastocysts, and no such allocyclic X chromosome was ever detected in X(M)X(M)Y blastocysts. In agreement with these findings, only one Xist paint signal was detected in 79% of X(M)X(M)X(P) cells, whereas no such signal was found in X(M)X(M)Y embryos. Thus, the present study supports the hypothesis that two X chromosomes remaining active in the extraembryonic cell lineages due to the maternal imprinting explain the underdevelopment of extraembryonic structures and hence early postimplantation death of DsX(M) embryos.

Molecular and biochemical characterization of a serine proteinase predominantly expressed in the medulla oblongata and cerebellar white matter of mouse brain

A full-length cDNA clone of a serine proteinase, mouse brain serine proteinase (mBSP), was isolated from a mouse brain cDNA library. mBSP, which has been recently reported to be expressed in the hair follicles of nude mice, is most similar (88% identical) in sequence to rat myelencephalon-specific protease. The mBSP mRNA was steadily expressed in the brain of adult mice with a transient expression in the early fetal stage during development. The genomic structure of the mouse gene for mBSP was determined. The gene, which is mapped to chromosome 7B4-B5, is about 7.4 kilobases in size and contains 7 exons. Interestingly, the 5'-untranslated region of the mBSP gene was interrupted by two introns. In situ hybridization analyses revealed that mBSP is expressed in the white matter of the cerebellum, medulla oblongata, and capsula interna and capsula interna pars retrolenticularis of mouse brain. Further, mBSP was immunolocalized to the neuroglial cells in the white matter of the cerebellum. Recombinant mBSP was produced in the bacterial expression system and activated by lysyl endopeptidase digestion, and the activated enzyme was purified for characterization. The enzyme showed amidolytic activities preferentially cleaving Arg-X bonds when 4-methylcoumaryl-7-amide-containing peptide substrates were used. Typical serine proteinase inhibitors, such as diisopropyl fluorophosphates, phenylmethanesulfonyl fluoride, soybean trypsin inhibitor, aprotinin, leupeptin, antipain, and benzamidine, strongly inhibited the enzyme activity. The recombinant mBSP effectively hydrolyzed fibronectin and gelatin, but not laminin, collagens I and IV, or elastin. These results suggest that mBSP plays an important role in association with the function of the adult mouse brain.

Trans-mesosigmoid cutaneous ureterostomy

BACKGROUND

A new method was developed in order to create a single stoma cutaneous ureterostomy in which both ureters traverse the abdominal cavity and yet are buttressed by the mesosigmoid and covered by its visceral peritoneum.

METHODS

The long mesenterium which is attached to the most mobile part of the sigmoid colon was used for the bilateral ureteral pathway. Tunnels for the ureteral path were made just underneath the visceral peritoneum on the bilateral side of the mesosigmoid. Through the tunnels both ureteral ends were brought from the retroperitoneal space to the mesenterocolonic junction (MCJ) and the MCJ is then approximated and sutured to the inside of the ureteral tract through the abdominal wall. The ureters brought outside the skin, are conjoined and sutured to the V skin flap. Eight patients who carried a high risk for operation and/or had a bladder tumor judged to be incurable underwent this cutaneous ureterostomy.

RESULTS

All cases except one with low urinary output could be managed without catheter indwelling during the follow-up period. Three patients suffered from paralytic ileus and one required laparotomy for mechanical ileus during the short postoperative period. Postoperative excretory urography evaluated 14 kidneys during the follow-up period from 2 to 61 months and showed normal upper urinary tract in 11 and a mildly hydronephrotic tract in three.

CONCLUSIONS

Transmesosigmoid cutaneous ureterostomy provides a single catheterless stoma even when the available ureters are relatively short. It appears to be a good method for supravesical urinary diversion when indicated.

Altered association of protein tyrosine kinases with postsynaptic densities after transient cerebral ischemia in the rat brain

Transient cerebral ischemia results in an increase in the tyrosine phosphorylation of proteins associated with postsynaptic densities (PSDs). The authors investigated the possible mechanisms behind this increase by analyzing isolated PSDs for protein tyrosine kinase activity and for the presence of specific tyrosine kinases. Transient (15 minutes) global ischemia was produced in adult rats by four-vessel occlusion, and PSDs were isolated immediately after ischemia or after 20 minutes or 6 hours of reperfusion. Tyrosine phosphorylation of several PSD proteins, including the N-methyl-D-aspartate (NMDA) receptor subunits NR2A and NR2B, was enhanced relative to shams after 20 minutes of reperfusion and underwent a further increase between 20 minutes and 6 hours. The ability of intrinsic PSD tyrosine kinase to phosphorylate PSD proteins, including the NMDA receptor, increased threefold after ischemia. Whereas PSD-associated proline-rich tyrosine kinase 2 (PYK2) and gp145TrkB were elevated immediately after the ischemic event, increases in Src and Fyn were not apparent until 6 hours of reperfusion. The level of PSD-associated pp125FAK decreased after ischemia. The results demonstrate that ischemia results in selective changes in the association of protein tyrosine kinases with the PSD which may account for ischemia-induced increases in the tyrosine phosphorylation of PSD proteins.

The cell cycle control gene ZAC/PLAGL1 is imprinted--a strong candidate gene for transient neonatal diabetes

We describe a screen for new imprinted human genes, and the identification in this way of ZAC (zinc finger protein which regulates apoptosis and cell cycle arrest)/ PLAGL1 (pleomorphicadenoma of the salivary gland gene like 1) as a strong candidate gene for transient neonatal diabetes mellitus (TNDM). To screen for imprinted genes, we compared parthenogenetic DNA from the chimeric patient FD and androgenetic DNA from hydatidiform mole, using restriction landmark genome scanning for methylation. This resulted in identification of two novel imprinted loci, one of which (NV149) we mapped to the TNDM region of 6q24. From analysis of the corresponding genomic region, it was determined that NV149 lies approximately 60 kb upstream of the ZAC / PLAGL1 gene. RT-PCR analysis was used to confirm that this ZAC / PLAGL1 is expressed only from the paternal allele in a variety of tissues. TNDM is known to result from upregulation of a paternally expressed gene on chromosome 6q24. The paternal expression, map position and known biological properties of ZAC / PLAGL1 make it highly likely that it is the TNDM gene. In particular, ZAC / PLAGL1 is a transcriptional regulator of the type 1 receptor for pituitary adenylate cyclase-activating polypeptide, which is the most potent known insulin secretagog and an important mediator of autocrine control of insulin secretion in the pancreatic islet.

X chromosome inactivation revealed by the X-linked lacZ transgene activity in periimplantation mouse embryos

Using H253 mouse stock harboring X-linked HMG-lacZ transgene, we examined X chromosome inactivation patterns in sectioned early female embryos. X-gal staining patterns were generally consistent with the paternal X inactivation in the trophectoderm and the primitive endoderm cell lineages and random inactivation in the epiblast lineages. The occurrence of embryonic visceral endoderm cells apparently at variance with the paternal X chromosome inactivation in 7.5 dpc embryos was explained by the replacement of visceral endoderm cells with cells of epiblast origin. The frequency of cells negative for X-gal staining in 4.5-5.5 dpc XmXp* embryos fluctuated considerably especially in the extraembryonic ectoderm and the primitive endoderm, whereas it was less variable in the embryonic ectoderm. We could not, however, determine whether it is a normal phenomenon revealed for the first time by the use of HMG-lacZ transgene or an abnormality caused by the multicopy transgene.

Diabetes mellitus associated with rapidly progressive glomerulonephritis with perinuclear antineutrophil cytoplasm antibodies

A 55-year-old woman who had been treated for diabetes mellitus for twenty-five years developed interstitial pneumonia and rapidly progressive glomerulonephritis (RPGN). The findings of light microscopy revealed fibrocellular crescent formation in all glomeruli and infiltration of lymphoid cells in interstitium. There were no deposits in the intracapillary area and mesangial area on both immunofluorescence and electron microscopy. Her interstitial pneumonia improved with pulse therapy of methylprednisolone and her hematuria disappeared with mix treatment of cyclophosphamide and double filtration plasmapheresis (DFPP). Her serum creatinine level improved from 2.2 mg/dl to 1.5 mg/dl. Interstitial pneumonia and hematuria did not recur at twelve months after the first hospitalization. This report presents a rare case with RPGN associated with diabetes mellitus who recovered with combination therapy of cyclophosphamide, steroid and DFPP.

Acquired anomalous intrapulmonary venous connection secondary to pulmonary venous stenosis

An unusual case of acquired development of anomalous intrapulmonary venous connection with pulmonary venous stenosis is presented. Appearances on a chest radiograph resembled the "scimitar" sign in a patient with previous surgery for partial anomalous pulmonary venous return. Spiral CT and pulmonary arteriography showed stenosis of the right upper pulmonary vein and an anomalous intrapulmonary venous connection between the right upper pulmonary vein and the right lower pulmonary vein. We consider the slow progression of pulmonary vein stenosis led to anomalous intrapulmonary venous connection as an intrapulmonary collateral.

Altered interaction between PSD-95 and the NMDA receptor following transient global ischemia

The postsynaptic density (PSD) is a cytoskeletal specialization involved in the anchoring of neurotransmitter receptors and in regulating the response of postsynaptic neurons to synaptic stimulation. The postsynaptic protein PSD-95 binds to NMDA receptor subunits NR2A and NR2B and to signaling molecules such as neuronal nitric oxide synthase and p135synGAP. We investigated the effects of transient cerebral ischemia on protein interactions involving PSD-95 and the NMDA receptor in the rat hippocampus. Ischemia followed by reperfusion resulted in a decrease in the solubility of the NMDA receptor and PSD-95 in 1% sodium deoxycholate, the decrease being greater in the vulnerable CA1 hippocampal subfield than in the less sensitive CA3/dentate gyrus regions. Solubilization of the kainic acid receptor GluR6/7 and the PSD-95 binding proteins, neuronal nitric oxide synthase and p135synGAP, also decreased following ischemia. The association between PSD-95 and NR2A and NR2B, as indicated by coimmunoprecipitation, was less in postischemic samples than in sham-operated controls. Ischemia also resulted in a decrease in the size of protein complexes containing PSD-95, but had only a small effect on the size distribution of complexes containing the NMDA receptor. The results indicate that molecular interactions involving PSD-95 and the NMDA receptor are modified by an ischemic challenge.

Detection and cloning of an X-linked locus associated with a NotI site that is not methylated on mouse inactivated X chromosome by the RLGS-M method

In looking for genes that escape X chromosome inactivation, we scanned the methylation status of genomic DNA from XX, X0, and XY mice using the method of restriction landmark genomic scanning using methylation-sensitive endonuclease. We detected and cloned a candidate locus and identified the Orf1 gene. Orf1 has sequence similarities to the B2 repetitive element and human CXORF4 (formerly called EXLM1), which escapes X inactivation. The B2 element spans the 3' terminus of the ORF and the 3' UTR of Orf1. The Orf1 gene encompasses 18.5 kb of genomic DNA including 11 exons and 10 introns. Taking advantage of genomic polymorphisms present between MSM and C3H/He, we showed that murine Orf1 is mapped to the proximal region of the X chromosome. Despite the unmethylation of the NotI site, Orf1 is subject to X inactivation.

Effects of amino acid replacements around the reactive site of chicken ovomucoid domain 3 on the inhibitory activity toward chymotrypsin and trypsin

We have previously shown that replacing the P1-site residue (Ala) of chicken ovomucoid domain 3 (OMCHI3) with a Met or Lys results in the acquisition of inhibitory activity toward chymotrypsin or trypsin, respectively. However, the inhibitory activities thus induced are not strong. In the present study, we introduced additional amino acid replacements around the reactive site to try to make the P1-site mutants more effective inhibitors of chymotrypsin or trypsin. The amino acid replacement Asp-->Tyr at the P2' site of OMCHI3(P1Met) resulted in conversion to a 35000-fold more effective inhibitor of chymotrypsin with an inhibitor constant (K(i)) of 1. 17x10(-11) M. The K(i) value of OMCHI3(P1Met, P2'Ala) indicated that the effect on the interaction with chymotrypsin of removing a negative charge from the P2' site was greater than that of introducing an aromatic ring. Similarly, enhanced inhibition of trypsin was observed when the Asp-->Tyr replacement was introduced into the P2' site of OMCHI3(P1Lys). Two additional replacements, Asp-->Ala at the P4 site and Arg-->Ala at the P3' site, made the mutant a more effective inhibitor of trypsin with a K(i) value of 1. 44x10(-9) M. By contrast, Arg-->Ala replacement at the P3' site of OMCHI3(P1Met, P2'Tyr) resulted in a greatly reduced inhibition of chymotrypsin, and Asp-->Ala replacement at the P4 site produced only a small change when compared with a natural variant of OMCHI3. These results clearly indicate that not only the P1-site residue but also the characteristics, particularly the electrostatic properties, of the amino acid residues around the reactive site of the protease inhibitor determine the strength of its interactions with proteases. Furthermore, amino acids with different characteristics are required around the reactive site for strong inhibition of chymotrypsin and trypsin.

Structure and localization of the mouse prolyl oligopeptidase gene

We have cloned and characterized the genomic structure of the mouse gene for prolyl oligopeptidase that is mapped to chromosome 10B2-B3. The gene is about 92 kilobases in size and contains 15 exons. All exon-intron junction sequences conform to the GT/AG rule. Comparison with the presumed domain structures of the mouse prolyl oligopeptidase indicates that the propeller domain of the enzyme is encoded by exons 3-10, whereas the catalytic domain is encoded by exons 1-3 and 10-15. The catalytic triad residues are encoded by two exons (Ser(554) on exon 13 and His(680) and Asp(642) on exon 15). The 5'-flanking region of the mouse prolyl oligopeptidase gene has structural features found in housekeeping gene promoters, including a GC-rich segment and an absence of TATA and CAAT boxes. A primer extension assay showed the presence of multiple sites for the initiation of transcription. Transient transfection analysis demonstrated that the 5'-flanking region of the gene can direct efficient expression in COS1 cells. Deletion studies revealed that the downstream 125-base pair sequence of the region is required for promoter activity in the cells.

The effect of transient global ischemia on the interaction of Src and Fyn with the N-methyl-D-aspartate receptor and postsynaptic densities: possible involvement of Src homology 2 domains

Transient ischemia increases tyrosine phosphorylation of N-methyl-D-aspartate (NMDA) receptor subunits NR2A and NR2B in the rat hippocampus. The authors investigated the effects of this increase on the ability of the receptor subunits to bind to the Src homology 2 (SH2) domains of Src and Fyn expressed as glutathione-S-transferase-SH2 fusion proteins. The NR2A and NR2B bound to each of the SH2 domains and binding was increased approximately twofold after ischemia and reperfusion. Binding was prevented by prior incubation of hippocampal homogenates with a protein tyrosine phosphatase or by a competing peptide for the Src SH2 domain. Ischemia induced a marked increase in the tyrosine phosphorylation of several proteins in the postsynaptic density (PSD), including NR2A and NR2B, but had no effect on the amounts of individual NMDA receptor subunits in the PSD. The level of Src and Fyn in PSDs, but not in other subcellular fractions, was increased after ischemia. The ischemia-induced increase in the interaction of NR2A and NR2B with the SH2 domains of Src and Fyn suggests a possible mechanism for the recruitment of signaling proteins to the PSD and may contribute to altered signal transduction in the postischemic hippocampus.

Compact chromatin packaging of inactive X chromosome involves the actively transcribed Xist gene

The Xist gene responsible for X inactivation may take a unique chromatin structure because of exceptional expression from inactive X Chromosome, (Chr). We have examined differential chromatin packaging of the Xist gene region between active and inactive X Chr with a novel method consisting of the chromatin fractionation and allele-specific detection. Analysis of F1 heterozygous female mice from T(X;16)16H x MSM crosses and two cell clones derived from inter-subspecific F1 female mice demonstrated that the packaging level of the transcribed Xist region on inactive X Chr was as tight as that of the repressed Pgk-1 allele on the same chromosome. On the other hand, restriction endonuclease sensitivity assay of chromatin showed that the promoter region, but not transcribed regions, of the transcribed Xist allele retained accessibility to nucleases. These results may suggest a cis-element(s) in a regulatory region of the Xist gene to prevent the transcriptionally inhibitory effect of the chromatin packaging.

Molecular cloning of antisense transcripts of the mouse Xist gene

Prior to X-inactivation, Xist is transcribed in unstable form. The initiation of X-inactivation is associated with the appearance of stable Xist transcripts which coat the X chromosome to be inactivated. Using strand specific RT-PCR analysis of the 5' region of Xist, we have detected antisense transcripts (Xist AS) in undifferentiated embryonic stem (ES) cells, but not in female somatic cells. Screening of a female ES cell cDNA library allowed us to isolate one poly(A)-tailed cDNA clone corresponding to this RNA. 5' RACE analysis showed that XistAS and the P1 sense product of Xist overlap by at least 707 bp. Expression of XistAS was also detected in early mouse embryos before random X-inactivation in the epiblast lineage. Although XistAS is low in abundance, it may be involved in destabilizing Xist mRNA in undifferentiated ES cells.

Microsphere embolism-induced elevation of nerve growth factor level and appearance of nerve growth factor immunoreactivity in activated T-lymphocytes in the rat brain

Changes in nerve growth factor (NGF) level and type of cells producing NGF were investigated in the rat brain after sustained cerebral embolism. The NGF level was determined by a two-site enzyme immunoassay specific for NGF. The cerebral cortex, striatum, and hippocampus of the embolized hemisphere maximally contained 2.4-, 2.4-, and 1.7-times higher NGF levels than the corresponding regions of the nonembolized hemisphere. A significant increase was transiently observed for 1 week in the cerebral cortex and striatum, whereas the increase was longer lasting, at least of 4 weeks' duration, in the hippocampus. To examine the localization of NGF-like immunoreactivity (NGF-LI), we used a newly developed anti-NGF peptide antiserum that specifically recognized a 30-kDa molecule(s) in the hippocampal extracts or in NGF cDNA-transfected cells, suggesting that the antibody predominantly reacted with the putative NGF precursor protein(s). NGF-LI, which was localized in neurons of the normal or non-embolized hemisphere, was reduced, and on the embolized side new signals emerged in small non-neuronal cells having a round shape. These included cells with common leukocyte antigen CD45 and T-lymphocyte antigen CD3, which did not appear in the normal or non-embolized hemisphere. NGF-LI and CD3 were colocalized in a substantial number of the cells, suggesting that some activated T-lymphocytes produce NGF for neuronal regeneration after sustained cerebral embolism.

Severe hyperparathyroidism with hypercalcemia associated with chronic renal failure at pre-dialysis stage

We report a case of a 23-year-old Japanese woman who had severe hyperparathyroidism associated with chronic renal failure before the start of dialysis treatment. Her chief complaints were swelling and pain in both shoulders. Laboratory examination revealed renal failure (BUN 134 mg/dl, serum Cr 7.3 mg/dl), severe normocytic normochromic anemia (hemoglobin 4.3 g/dl), hypercalcemia (11.8 mg/dl), and hyperphosphatemia (9.7 mg/dl). Serum PTH levels were extremely increased (intact PTH >1,000 pg/ml: normal range 10-50 pg/ml). X-ray examination of the skull and shoulders showed a salt and pepper appearance, and cauliflower-like deformity of the distal end of both clavicles, respectively. Accelerated ectopic calcification was observed in the costal cartilages, internal carotid arteries, and splenic arteries. Ultrasonographic examination revealed enlargement of the four parathyroid glands. Thallium-technetium subtraction scintigraphy of the parathyroid glands showed increased uptake into the upper two. Renal needle biopsy revealed severe impairment of the interstitium and tubules with much milder changes in glomeruli. The etiology of the renal failure could not be identified. Hemodialysis, total parathyroidectomy and auto-transplantation into the forearm were immediately performed. The pathological diagnosis was chief cell hyperplasia of the parathyroid glands. Based on the presence of chronic renal failure, remarkable hyperphosphatemia with mild hypercalcemia, an unusually high level of serum PTH, and accelerated ectopic calcification, the patient was diagnosed to have severe secondary hyperparathyroidism caused by chronic renal failure with major impairment of the renal interstitium and tubules.

Effect of CpG methylation on expression of the mouse imprinted gene Mest

We previously reported isolation of the mouse gene, Mest (mesoderm-specific transcripts), which is mapped to the proximal part of chromosome 6 and predominantly expressed in the mesoderm and its derivatives during development. Peg1, a paternally expressed gene isolated by a systematic screening of imprinted genes, was recently demonstrated to be identical to Mest. We and others have shown that the human homolog (MEST) of Mest is also imprinted so as to be expressed from the paternal copy and maps to 7q32. To study transcriptional regulation of Mest/Peg1, we examined the effect of DNA methylation on its expression. In the embryonal carcinoma (EC) cell line, MC12, from which Mest was originally isolated, the 5'-region harboring presumptive promoter of the gene was undermethylated. On the other hand, C4XX, a subclone of MC12 which had lost expression of Mest, was characterized by extremely high levels of methylation in the 5'-region, demethylation of which resulted in activation of Mest. Furthermore, a methylated reporter construct with the luciferase gene under the control of the putative promoter region of Mest was not competent to produce luciferase activity in MC12 cells. These results suggest a suppressive role for DNA methylation in Mest expression. However, neither methylated nor unmethylated reporter constructs showed luciferase activity in a primary culture from the adult kidney, in which Mest is down-regulated despite apparent unmethylation of the paternal allele. Taken together, the data suggest that there are probably two modes of regulation for the Mest gene; one being a methylation-dependent mechanism that regulates imprinted expression of Mest during development, and the other being a methylation-independent mechanism that is involved in down-regulation of Mest in adult tissues.

Renin-angiotensin system and fibronectin gene expression in Dahl Iwai salt-sensitive and salt-resistant rats

OBJECTIVE

The tissue renin-angiotensin system and extracellular matrix are involved in the cardiovascular hypertrophy and remodeling induced by hypertension. In this study, we examined the gene expression of the tissue renin-angiotensin system and fibronectin in inbred Dahl Iwai salt-sensitive and salt-resistant rats.

MATERIALS AND METHODS

Eight pairs of 6-week-old male Dahl Iwai salt-sensitive and salt-resistant rats were fed either a low- or high-salt diet (0.3% or 8% NaCl, respectively) for 4 weeks. Activities of the circulating renin-angiotensin system were measured by radioimmunoassay and the gene expression of tissue angiotensinogen, the angiotensin II type 1 receptor (AT1) and fibronectin were analyzed by Northern blot analysis.

RESULTS

Salt loading significantly increased blood pressure and produced cardiovascular hypertrophy and nephrosclerosis in the salt-sensitive rats. Activities of the circulating renin-angiotensin system were lower in salt-sensitive rats than in salt-resistant rats fed the low-salt diet, and salt loading lowered these activities in salt-resistant rats but not in salt-sensitive rats. In salt-resistant rats, salt loading increased renal, cardiac and aortic angiotensinogen, AT1 and fibronectin messenger (m)RNA expression except for aortic fibronectin mRNA expression. In contrast, in the salt-sensitive rats, salt loading stimulated the expression of cardiac fibronectin and aortic angiotensinogen, AT1 and fibronectin mRNAs. Furthermore, the cardiac and aortic fibronectin mRNA levels in salt-sensitive rats were higher than those in salt-resistant rats when both strains were fed the high-salt diet.

CONCLUSIONS

These results demonstrate that the expression of tissue angiotensinogen, AT1 and fibronectin mRNAs is regulated differently in Dahl Iwai salt-sensitive and salt-resistant rats, and indicate that salt-mediated hypertension activates the cardiac fibronectin gene independently of the tissue renin-angiotensin system and stimulates the aortic fibronectin gene with activation of the tissue renin-angiotensin system.

Simultaneous improvement of minimal-change nephrotic syndrome and anemia with steroid therapy

A 56-year-old man presented with transient anemia in minimal-change nephrotic syndrome. Following nephrotic syndrome, anemia suddenly appeared without renal dysfunction. The anemia might be attributable to hemodilution because of significant correlations between the values of hemoglobin concentration and serum total protein or blood urea nitrogen during the clinical course. A low serum level and a low urinary excretion of erythropoietin were found, and when nephrotic syndrome ameliorated with steroid therapy, urinary erythropoietin excretion and anemia disappeared. This case indicated disappearance of the exponential increase of endogenous erythropoietin in acute anemia in nephrotic syndrome probably due to urinary losses and altered biosynthesis of erythropoietin. We report a case of the simultaneous improvement of both nephrotic syndrome and anemia with steroid therapy.

Blockage of interleukin-6 receptor ameliorates joint disease in murine collagen-induced arthritis

OBJECTIVE

To clarify the role of interleukin-6 (IL-6) in the pathogenesis of collagen-induced arthritis (CIA).

METHODS

CIA was induced by immunizing twice at a 3-week interval with bovine type II collagen (CII) emulsified with complete adjuvant. Rat anti-mouse IL-6 receptor (anti-IL-6R) monoclonal antibody MR16-1 or isotype-matched control antibody KH-5 was then injected once intraperitoneally. Symptoms of arthritis were evaluated with a visual scoring system, and serum anti-CII antibody and IL-6 levels were measured by enzyme-linked immunosorbent assay. In addition, the CII responsiveness of splenic lymphocytes from mice with CIA was examined.

RESULTS

In mice with CIA, excess production of IL-6 in sera was observed within 24 hours after the first CII immunization, and then rapidly decreased. Serum IL-6 increased again beginning 14 days after immunization, in conjunction with the onset of arthritis. When MR16-1 was injected immediately after immunization with CII, it inhibited the development of arthritis in a dose-dependent manner. Furthermore, MR16-1-treated mice exhibited lower serum levels of IgG anti-CII antibody and reduced responsiveness of lymphocytes to CII. This suppressive effect was observed when MR16-1 was injected on day 0 or 3, but not when injected on day 7 or 14.

CONCLUSION

IL-6 produced after CII immunization appears to play an essential role in the immunity to CII, and anti-IL-6R antibody reduces the development of CIA by suppressing IL-6 signal transduction.

Wilms' tumor suppressor gene (WT1) as a target gene of SRY function in a mouse ES cell line transfected with SRY

With the aim of identifying the gene(s) located downstream from SRY, we transfected an ES cell line with XX karyotype, TMA-18, with a Sry DNA construct and established cell lines, TS18-1 and TS18-2, where the transfected Sry was expressed in the functional linear mRNA form. Among the five potential SRY-target genes examined, i.e., MIS, SF1, P450arom, Sox9 and WT1, only the expression of WT1 was induced de novo by the unscheduled expression of Sry in the transfected cell lines. No clear indication of Sry-induced enhancement of Sox9 expression was obtained in the present series of experiments. Function of a yet unidentified gene(s) located on the Y chromosome might be needed for the up-regulation of Sox 9 expression which takes place during the development of male gonads. Quantitative RT-PCR analysis of the patterns of WT1 expression in developing fetal gonads revealed that although both male and female fetal gonads express WT1, male gonads invariably expressed WT1 mRNA at higher levels than female ones after the Sry expression. Immunohistochemical analysis of the male fetal gonads between 10.5 and 13.5 dpc demonstrated the presence of strong WT1 immunoreactivity in Sertoli cells of the primordial testes. Suggestions were made in the past indicating that both SF1 and WT1 proteins might be active in a common pathway upstream from Sry. Our results showed that WT1 is located downstream, rather than upstream from Sry and behaves independently from SF1. Analysis using an appropriate in vitro system will be essential to understand the molecular mechanisms of SRY action within cells.

Mechanism of angiotensin II-mediated regulation of fibronectin gene in rat vascular smooth muscle cells

This study was performed to investigate a mechanism of angiotensin II (Ang II)-mediated activation of the fibronectin (FN) gene in rat vascular smooth muscle cells. Actinomycin D and CV11974 completely inhibited Ang II-mediated increase in FN mRNA levels. Inhibitors of protein kinase C (PKC), protein-tyrosine kinase (PTK), phosphatidylinositol-specific phospholipase C, Ras, phosphatidylinositol 3-kinase, p70 S6 kinase, and Ca2+/calmodulin kinase also decreased Ang II-induced activation of FN mRNA. In contrast, cycloheximide; PD123319; or inhibitors of Gi, protein kinase A, or mitogen-activated protein kinase kinase did not affect the induction. FN promoter contained a putative AP-1 binding site (rFN/AP-1; -463 to -437), and the results of a transient transfection and electrophoretic mobility shift assay showed that Ang II enhanced rFN/AP-1 activity. CV11974 and inhibitors of PKC or PTK suppressed Ang II-mediated increases in rFN/AP-1 activity, although neither PD123319 nor a protein kinase A inhibitor affected the induction. Furthermore, mutation of rFN/AP-1 that disrupted nuclear binding suppressed Ang II-induced transcription in the native FN promoter (-1908 to +136) context. Thus, Ang II activates transcription of the FN gene through the Ang II type 1 receptor in vascular smooth muscle cells, at least in part, via the activation of AP-1 by a signaling mechanism dependent on PKC and PTK.

Tetraploid embryos rescue embryonic lethality caused by an additional maternally inherited X chromosome in the mouse

Mouse embryos with an additional maternally inherited X chromosome, i.e., disomic for XM (DsXM), cease to grow early in development and have a deficient extraembryonic region. We hypothesized that the underdeveloped extraembryonic region is attributed to two copies of XM that escape inactivation due to maternal imprinting. To examine the validity of this hypothesis and throw more light on the significance of X chromosome dosage on cell differentiation, we generated DsXM(XMXMXP and XMXMY) embryos at a high frequency taking advantage of the elevated incidence of X chromosome nondisjunction in female mice heterozygous for two Robertsonian X-autosome translocations, Rb(X.2)2Ad and Rb(X.9)6H. Although two XM chromosomes seem to remain active in both trophectoderm and primitive endoderm, detailed histological examination showed that the polar trophectoderm derivatives (ectoplacental cone and extraembryonic ectoderm) are severely affected, but the primitive endoderm derivatives (visceral and parietal endoderm) are relatively unaffected. Successful rescue of DsXM embryos by aggregation with tetraploid embryos show that X chromosome inactivation occurred normally leaving one X active in epiblast derivatives. Thus, two copies of active XM chromosome in cells of the polar trophectoderm cell lineage seem to be the main cause of early lethality shown by DsXM embryos as a result of failure in formation of ectoplacental cone and extraembryonic ectoderm.

Decreased expression and functionality of NMDA receptor complexes persist in the CA1, but not in the dentate gyrus after transient cerebral ischemia

The authors investigated the gene expression of the NR2A and NR2B subunits of N-methyl-D-aspartate (NMDA) receptor and the functional electrophysiologic activity of NMDA receptor complexes in the vulnerable CA1 and less vulnerable dentate gyrus subfields of the rat hippocampus at different times after transient cerebral ischemia. Decreased expression for both subtypes was observed in both the CA1 subfield and dentate granule cell layer at early times after challenge; however, the decreased expression in the dentate granule cell layer was reversible because mRNA levels for both the NR2A and NR2B subtypes recovered to, or surpassed, sham-operated mRNA levels by 3 days postchallenge. No recovery of expression for either subtype was observed in the CA1 subfield. The functional activity of NMDA receptor complexes, as assessed by slow field excitatory postsynaptic potentiations (slow f-EPSP) in CA1 pyramidal neurons, was maintained at 6 hours postchallenge; however, this activity was diminished greatly by 24 hours postchallenge, and absent at 7 days postchallenge. A similar pattern was observed for the non-NMDA receptor-mediated fast f-EPSP. In dentate granule neurons, however, no significant change in NMDA receptor-mediated slow f-EPSP from sham control was observed at any time after insult. The non-NMDA receptor-generated fast f-EPSPs also were maintained at all times postinsult in the dentate gyrus. These results illustrate that the activity of NMDA receptors remains functional in dentate granule neurons, but not in the pyramidal neurons of the CA1 subfield, at early and intermediate times after transient cerebral ischemia, and suggest that there is a differential effect of ischemia on the glutamatergic transmission systems in these two hippocampal subfields.

[Operative results and long-term prognosis of type A acute aortic dissection]

Between 1983 and 1997, we operated upon 91 patients with type A acute aortic dissection. The dissection was localized in 22 patients and extensive in 69 patients. All patients underwent graft replacement and 61 (67%) patients underwent simultaneous replacement of ascending aorta and total aortic arch. The hospital mortality rate were 9% for the localized dissection and 21% for the extensive dissection. The actuarial survival rates in patients with localized dissection at 5 and at 10 years was 91% and 76%, whereas those in patients with extensive dissection at 5 and at 10 years was 68% and 62%. The freedom from dissection related death or reoperation in operative survivors with localized dissection at 5 and at 10 years was 100% and 83%, whereas those in patients with extensive dissection at 5 and at 10 years was 78% and 56%. The simultaneous replacement of ascending aorta and total aortic arch in patients with extensive dissection was effective to obliteration of the distal false channel, although this extended procedure has to be carefully adopted in high risk patients with associated complications such as acute dissection organ ischemia.

Diagnostic value of the Amplicor PCR assay for initial diagnosis and assessment of treatment response for pulmonary tuberculosis

We evaluated the Amplicor PCR assay as an initial diagnostic tool on the basis of clinical diagnosis, and assessed this assay as a follow-up test for patients with pulmonary tuberculosis during chemotherapy. Of the 208 specimens from 155 patients who were bacteriologically and/or clinically diagnosed with active tuberculosis before chemotherapy, 144 were Amplicor PCR-positive (sensitivity, 69.2%), which was equal to the results of culturing. Among 89 specimens which showed positive results by smear and culturing, the Amplicor PCR assay detected 87 (97.8%), whereas among 55 specimens which showed smear-negative but culture-positive results, the Amplicor PCR assay detected 46 (83.6 %)(P= 0.003). No false positive results were found in the two systems (specificity, 100%, 120/120). The Amplicor PCR assay was also evaluated as a follow-up test using 926 specimens from 207 patients receiving active tuberculosis chemotherapy. Among 433 specimens which showed Amplicor-PCR positive, 222 (51.3%) were culture-negative. On the other hand, among 233 culture-positive specimens, only 12 (5.2%) were Amplicor PCR-negative. Therefore, this assay is useful for the rapid diagnosis of tuberculosis. The duration of Amplicor PCR-positive after culture-negative conversion was significantly associated with the presence of cavitary lesion, smear-positive specimens before treatment, and smear-positive specimens with negative cultures during chemotherapy.

IL-6 receptor blockage inhibits the onset of autoimmune kidney disease in NZB/W F1 mice

In the present study, we examined the preventive effect of anti-mouse IL-6 receptor (IL-6R) antibody, MR16-1, on the development of autoimmune kidney disease in female NZB/W F1 (BWF1) mice. Immunological tolerance to MR16-1 or isotype-matched control antibody, KH-5, was induced by the simultaneous administration of anti-CD4 MoAb in mice. Thereafter, mice were intraperitoneally given 0.5 mg of MR16-1, 0.5 mg of KH-5 or saline once a week from 13 to 64 weeks of age. MR16-1 treatment dramatically suppressed proteinuria and prolonged the survival time of BWF1 mice. Only one out of 10 mice died with high levels of proteinuria throughout the experiment. MR16-1 almost completely suppressed the production of IgG forms of anti-DNA and anti-TNP antibodies, but not the IgM forms of these antibodies. In particular, all IgG subclasses (IgG1, IgG2a, IgG2b and IgG3) of anti-DNA antibody production were significantly suppressed. Moreover, serum IgG1, IgG2a and IgG3 levels in MR16-1-treated mice were lower than those in saline- and KH-5-treated mice, whereas serum IgM and IgA levels were not influenced. In conclusion, MR16-1 potently suppressed the development of autoimmune disease in BWF1 mice, and this was attributed to its effect of specific suppression of IgG class antibody production.

Trisomy 8 does not affect differentiative potential in a murine parthenogenetic embryonic stem cell line

Murine parthenogenetic embryonic stem (ES) cell lines expressing lac Z reporter gene were isolated after co-transfection with lac Z reporter gene (pENL) and neo gene (pSTneo) to TMA-48P cell line of 129/Sv origin. Karyotype analyses showed that all of four transfected cell lines examined contained 41 chromosomes with trisomy 8. Bacterial neo transgene required for G418 selection were integrated into several chromosomes including chromosome 8. Histological studies of teratomas formed in syngenic mice and embryoid bodies grown in vitro showed that the differentiative potential remained almost identical in chromosomally normal parental cell line and its derivative cell lines trisomic for chromosome 8.

Differentiative potential of a mouse parthenogenetic embryonic stem cell line revealed by embryoid body formation in vitro

The in vitro differentiative potential of mouse parthenogenetic (PG) embryonic stem (PGES) cells were investigated in the formation of embryoid bodies (EBs). EBs derived from PGES cells retarded in growth and showed restricted differentiation compared to their fertilized counterpart. In chimeric EBs from the aggregation of PGES and fertilized ES cells, morphological examination revealed that PGES cells were reduced in their population and distributed in endodermal layer as culture periods proceeded. These findings were comparable to those in aggregation chimeras of fertilized and PG embryos, and suggest that the differentiation of PGES cells in vitro is restricted in the formation of EBs.

Polymerase chain reaction of pleural biopsy specimens for rapid diagnosis of tuberculous pleuritis

SETTING

Government-administered regional teaching hospital.

OBJECTIVE

To improve timeliness and sensitivity of laboratory diagnosis of tuberculous pleuritis.

DESIGN

We applied polymerase chain reaction (PCR) to detect DNA (IS6110) specific for Mycobacterium tuberculosis complex in pleural biopsy specimens.

RESULTS

Of 28 patients with pleural disease, 11 were diagnosed by microbiology (smear/culture of sputum or pleural fluid) with tuberculous pleuritis, eight were diagnosed with tuberculous pleuritis by histology (of pleural biopsies) and/or clinical presentation, and nine were diagnosed with carcinomatous pleuritis. Seventeen of the patients' pleural biopsies were PCR positive. Based on microbiological results, the sensitivity of the PCR assay was 100% (11/11). On the other hand, based on the results of the histological and clinical data, sensitivity and specificity of the PCR results were 89% (17/19) and 100% (9/9), respectively.

CONCLUSION

PCR of pleural biopsy specimens can be a useful method when employed in combination with microbiological and histological examinations of pleural biopsy for rapid diagnosis of tuberculous pleuritis.

Reversed-phase ion-pair chromatographic analysis of tetracycline antibiotics. Application to discolored teeth

A high-performance liquid chromatographic method with diode array detection was developed to simultaneously separate tetracycline antibiotics and applied to the analysis of discolored teeth. By a reversed-phase ion-pair chromatographic system using pentanesulfonate as a counter ion, minocycline, oxytetracycline, tetracycline and demeclocycline were eluted in this order, and they showed base-line separation within 9 min. When using oxytetracycline as an internal standard, the quantitative ranges were between 2.5 ng/ml and 7.5 microg/ml. Powdered dentine (10 mg) and enamel (40 mg) prepared from discolored primary teeth were sonicated in 0.25 ml of 10 mM HCl containing oxytetracycline (0.75 microg/ml) and 50 mM EDTA-2Na, thereafter the supernatants were chromatographed. Eluates from both discolored tooth samples were identified as minocycline based on diode array spectra of their peaks, while minocycline was not detected in any samples from nondiscolored normal teeth, indicating that discoloration of the tested teeth was due to minocycline incorporated into dentine and enamel. Replicate quantitative analyses of the identical tooth substances showed that intra- and inter-assay C.V.s were 2.63 and 4.95% for dentine, and 5.42 and 10.88% for enamel. Application of the developed method to nine discolored teeth revealed that the incorporated minocycline ranged from 20.13 to 84.62 ng/mg of dentine and 0.89 to 7.87 ng/mg of enamel.

Difference in chromatin packaging between active and inactive X chromosomes by fractionation and allele-specific detection

Using a novel method consisting of chromatin fractionation and allele-specific detection, chromatin packaging is compared between active X (Xa) and inactive X (Xi) chromosomes for five tumor cell clones that were derived from inter-subspecific F1 female mice. Separation of heterochromatic (H) and euchromatic (E) fractions is monitored by hybridization with subtelomeric satellite DNA and ribosomal RNA gene and by PCR amplification of p53 gene/pseudogene with one primer set. The H fraction was enriched with satellite and p53 pseudogene probably existing in heterochromatic regions while the E fraction showed inverse, suggesting fair separation. Analysis with seven marker and three gene loci revealed concentration of alleles on Xi in the H fraction and those on Xa in the E fraction, though the concentration levels varied. This implies that the packaging level of Xi is higher than that of active or inactive euchromatin on Xa. Intriguingly, one cell line showed biallelic expression and chromatin relaxation of the Pgk-1 locus, suggesting that the relaxation occur regionally on X chromosome.

Regulation of cardiac angiotensinogen mRNA in vivo and in vitro

In this study, to investigate the mechanism of hypertension-associated induction of cardiac angiotensinogen in vivo and in vitro, we studied the regulation of angiotensinogen mRNA in the hearts of genetically hypertensive rats and in the rat cardiomyocytes. Levels of cardiac angiotensinogen mRNA were significantly increased in the hypertensive rats. Steady state mRNA levels for angiotensinogen mRNA in cardiomyocytes were increased by angiotensin II and mechanical stretch. The addition of an angiotensin II type 1 receptor antagonist (CV11974) and a transcriptional inhibitor (actinomycin D) completely blocked the induction of angiotensinogen mRNA by angiotensin II in cardiomyocytes. The addition of CV11974 significantly, but not completely, inhibited the induction of angiotensinogen mRNA by mechanical stretch. Actinomycin D completely blocked the induction of angiotensinogen mRNA by stretch in cardiomyocytes. An angiotensin II type 2 receptor antagonist (PD123319) and a protein synthesis inhibitor (cycloheximide) did not affect the induction. These results indicate that the expression of cardiac angiotensinogen mRNA is activated by the development of hypertensive cardiac hypertrophy, and that angiotensin II and mechanical stretch activates the angiotensinogen gene via the angiotensin II type 1 receptor-pathway in cardiomyocytes.

[Reoperation after corrective surgery for tetralogy of Fallot]

Thirty-six patients (7.6%) underwent reoperation after total correction of tetralogy of Fallot in our institution from 1955 to 1997. Eight patients underwent a second reoperation in the same follow-up period. The indications for surgical repair were recurrent or residual lesions alone (Qp/Qs > or = 2.0, right ventricule-pulmonary artery pressure gradient > or = 50 mmHg, tricuspid regurgitation: (TR) > or = grade 3, pulmonary regurgitation (PR) > or grade 3), or in combination with other lesions. The reoperation consisted of closure of a residual VSD in 12 patients (33.3%), relief of right ventricular outflow obstruction in 12 (33.3%), tricuspid valve repair or replacement for TR in 11 (30.6%), and pulmonary valve repair or replacement for PR in 10 (27.8%). The indications for second reoperation consisted of mainly residual or recurrent TR or infections endocarditis. There was one operative death (2.8%) in the reoperation group and one death (12.5%) in the second reoperation group. Five patients (14.7%) died during a follow-up period of 1-25 years (mean 11.6 years). Twenty-none patients (80.6 %) survived surgery, and 25 (86.2%) are now in NYHA class I and 4 in class II. Reoperation and second reoperation are associated with a low mortality rate and good long-term results in our surgical experience.